HIV Nursing 2017; 17: 77–87 Continuing professional development HIV and renal disorders Juliet Bennett Independent Nurse Advisor Abstract Despite advances in HIV medicine it is widely and monitoring of the condition. A range of acknowledged that people living with HIV (PLWH) are interventions are available to minimise further at particular risk of renal problems although the deterioration and to treat end-stage renal disease. pattern of disease has changed significantly over time. There is a clear role for nurses working in the field Renal disease, also known as kidney disease or of HIV alongside multidisciplinary colleagues in the nephropathy, is currently one of the most common provision of evidence-based screening and care for non-infectious comorbidities seen among PLWH. It is those affected, in order to improve clinical outcomes vital that health care professionals are aware of this and quality of life. risk in order to facilitate early detection, assessment Key words: renal disease, HIV, assessment, monitoring, treatment Introduction quiz before reading the article, returning to it afterwards to see how much you have learned.) enal disease was recognised as a complication of HIV infection soon after the disease itself was B. Aims and intended learning R identified in the early 1980s. As the natural outcomes history of HIV infection evolves, and with the ageing cohort (plus increased exposure to potentially This article aims to increase knowledge and nephrotoxic medications), prevalence of other non- confidence. On completion of reading, undertaking infectious comorbidities, such as diabetes and the included activities and self-assessment quiz you cardiovascular disease (CVD), renal disease in people should be able to: living with HIV (PLWH) is also increasing and growing ■ Describe the structure and function of the healthy in importance. Renal disorders can occur at all stages kidney; of HIV infection. They range from acute kidney injury ■ List a range of investigations used to determine (AKI) and fluid and electrolyte imbalance to end-stage renal function and show an understanding of some renal disease (ESRD). HIV-associated nephropathy of their advantages and limitations; (HIVAN) is the most common form of kidney disease ■ Describe a number of risk factors for renal disease; amongst PLWH [1] and is still prevalent despite the ■ List a range of common symptoms of renal success of contemporary antiretroviral therapy (ART). dysfunction; Given that renal impairment is associated with ■ Describe the staging system for CKD; increased rates of morbidity and mortality, early ■ Outline the most common renal disorders found detection and effective management of associated in PLWH and explain some possible underlying risk factors may help to limit overall disease burden. HIV-related risk factors; This CPD article summarises normal kidney structure ■ Give the rationale for regular monitoring of renal and function, discusses risk factors, causes and function in PLWH; symptoms of renal disease, outlines acute renal failure ■ Summarise a variety of treatment options available (ARF) and then focuses on chronic kidney disease to those with renal disease and how these apply (CKD) and the pathogenesis and treatment of HIV- to PLWH in the era of successful ART. related renal disorders. C. Kidney anatomy and renal A. Revalidation function: a summary The kidneys are located at the rear of the abdominal This article has been prepared with continuing cavity in the retroperitoneal space. A normal, healthy professional development (CPD) in mind and can be kidney is bean-shaped and about 10–13 cm long, and used to support your revalidation. It is estimated that 5.0–7.5 cm wide in the average adult with the left 4 hours of CPD activity will be required for completion kidney being usually slightly larger than the right. of the reading, ‘Time out’ activities, the quiz and writing a reflective account in relation to your learning The main body of the kidney is divided into two and its applicability to your practice. (You could test major structures; the outer renal cortex and the your knowledge by completing the self-assessment inner medulla. These structures are divided into 77 Continuing professional development HIV Nursing 2017; 17: 77–87 cone-shaped segments and contain the renal cortex Time out activity 1 and surround a portion of the medulla (called the renal pyramid). Between the renal pyramids are Before reading on consider how much you can recall about projections of cortex called renal columns. Nephrons the function of the kidney? Make brief notes on the role of this span both the cortex and medulla. The initial section vital organ then compare them to the summary provided. of a nephron acts as a filter and flows into the renal corpuscle and this is followed by a renal tubule. The tip of each renal pyramid empties urine into a minor calyx then on to the major calyces and The kidneys have several vital functions, which are ultimately into the renal pelvis, which in turn becomes largely achieved through the mechanisms of filtration, the ureter. The left and right renal arteries supply the re-absorption, secretion and excretion: circulation directly from the abdominal aorta. Despite ■ their relatively small size, the kidneys are very well Excretion of waste products such as urea and uric perfused, receiving approximately 20% of cardiac acid ■ output. The regulation of fluid balance and blood pressure ■ Maintaining osmolarity, i.e. the regulation of water and salts Cortical ■ Acid/base homeostasis, i.e. the blood vessels Arcuate blood vessels stabilisation of pH Interlobar ■ The re-absorption of vital nutrients blood vessels Minor calyx such as glucose and amino Renal vein Major calyx acids Renal pelvis ■ The production of enzymes and Renal Renal hormones such as calcitriol, hilum nerve Pyramid erythropoietin and renin Renal artery Papilla Medulla Renal column Ureter Cortex Capsule D. Assessing renal Figure 1: Cross-section showing the structure of a healthy kidney function Renal function is an indication of the state of the The glomerulus is a network of capillaries located at kidney and its efficacy as previously stated. The the beginning of a nephron. It is surrounded by a sac glomerular filtration rate (GFR) describes the flow rate known as the Bowman’s capsule. A glomerulus and of filtered fluid through the kidney. Creatinine its surrounding Bowman’s capsule provide the basic clearance rate (CrCl) is the volume of blood plasma filtration unit for plasma. The rate at which blood is that is cleared of the waste product creatinine over filtered through all of these glomeruli is the glomerular time and is a measure for estimating the GFR. There filtration rate (GFR) and, therefore, provides a robust is a range of different equations for assessing renal marker of overall renal function. function with most taking into account the individual’s age, weight gender and race. Proximal convoluted Nephron tubule Peritubular Distal capillaries Efferent convoluted arteriole tubule Glomerulus Cortex Bowman’s capsule Collecting I. Urinalysis Afferent duct arteriole Renal Nurses are familiar with performing these pyramid Medulla quick and informative tests. Box 1 summarises the key findings in relation to renal function specifically. Note that the Loop of Henle urine dipstick analysis primarily detects albumin (rather than all proteins), useful Vasa recta as a marker of glomerular disease but this is inadequate in the detection of renal Figure 2: Structure of the glomerulus tubular disease. 78 HIV Nursing 2017; 17: 77–87 Continuing professional development sample to measure plasma creatinine is taken Box 1. Dipstick urinalysis: key findings in relation to renal alongside a timed urine collection (usually over 24 disorders hours) and both are used to calculate creatinine Visual appearance clearance. Colourless urine may indicate nephritis. Haematuria may be visible and can indicate a urinary tract III. Blood urea nitrogen infection, renal trauma, glomerulonephritis, nephrolithiasis or A blood urea nitrogen (BUN) result is often given malignancy. alongside the creatinine result and the ratio Dark urine often indicates dehydration. calculated. These tests are, however, rather limited by their time-consuming nature, problems with Specific gravity (SG) accurate urine collection (a single ’missed catch’ Hydrated patients will have an SG <1.010 whereas an SG >1.020 makes the test inaccurate) and also because they tend indicates dehydration. to overestimate the filtration rate. In addition levels pH are affected by age, gender, ethnic group, muscle bulk, ingestion of cooked meat, malnutrition and some This should range from 5–7, i.e. it is normally acidic, except after drugs, for example, the antibiotic trimethoprim. As a meal. a result these only provide a rough guide to renal Glucose function. The presence of glucose in urine may indicate a renal tubular disorder. IV. Estimated GFR GFR varies as a function of normal physiology as well Proteinuria as in the presence of disease. Its measurement is based The presence of protein in the urine may be caused by a on determining the volume of plasma from which a glomerular leak. substance is cleared by the glomerulus during its NICE guidance [2] highlights the importance of proteinuria as passage through the kidney. a marker for chronic kidney disease, which may be as significant as glomerular filtration rate (GFR). For all serum creatinine requests, laboratories should report an estimated GFR (eGFR) using a prediction Leukocytes equation, in addition to reporting the serum creatinine This relies on the reaction of leukocyte esterase produced result. An eGFR is currently the most frequently used by neutrophils and a positive result suggests urinary tract test of renal function and is recommended by NICE infection. [2]. Different equations exist to calculate this and accuracy can vary. The most recently advocated Nitrates formula was developed by the Modification of Diet Many Gram-negative and some Gram-positive bacteria are in Renal Disease (MDRD) Study Group [4] and most capable of producing this reaction and a positive test suggests laboratories in the UK now use this.